Recently, seafood is replacing livestock food in various countries. Particularly in Japan, various methods of processing fish and shellfish have been developed. These methods can be roughly classified into three categories, namely (A) utilizing the fishery products as a frozen meat source, (B) utilizing fish by retaining their shape as much as possible and (C) utilizing fish by breaking them into fine pieces. Method (A) is most popular in Japan. The meat source is this case is prepared by grinding fish meat and then freezing the resultant material in a block having a predetermined shape. From this block "kamaboko" and like kneaded seafoods can be produced. By this type of utility, the taste of fish and shellfish can be preserved. However, only limited kinds of fish and shellfish, mainly white meat fish, can be processed by this method. In addition, a great deal of man-hours are required to process the fishery products into a meat source. Further, the meat source has been developed as kneaded food and can find only limited utility, typically fried foods.
In method (B), only the meat of fishery products, mostly fish, are frozen for preservation, with head, bones and skin removed after catching the fish. The scope of application of this method, however, is limited mainly to large and medium size fish. Method (C) is for processing minced meat and fillets as raw material. In this method, fillets or the like are arranged into a square form and are then integrated by freezing. The method thus can find a wide scope of application to general fish and shellfish, and the processed fishery products may be utilized as material of Western foods as well. The frozen block obtained by this method, however, will be separated into the individual component fillets or meat pieces when it is unfrozen although the components are bound together while the block remains frozen. For this reason, the frozen block products can find little demand in Japan and other countries where exclusive household freezers or refrigerators having a large capacity freezing equipment are not prevalent.
Another drawback in method (C) is that fillets or like material must be packed in an accurate square shape in order to facilitate subsequent processing. Usually, the material is closely packed in a square frame made of a dimple carton or the like having recesses on the surface for integration by freezing.
This will be described in more detail. A square or rectangular frame structure is placed on a base board. A sheet having a number of recesses is then laid on the inner surface of the frame. Fillets or like material are then closely arranged on the sheet and integrated by freezing. The frame is then removed to obtain a frozen block of fillets or like material.
In this case, the fillets or like must of course be arranged closely and orderly even along the sides and at the corners of the frame. However, since the fillets are usually substantially triangular in shape, even in a very orderly arrangement they will inevitably contain considerable spaces defined by adjacent ones of them. At any rate, preparation of a neat frozen block is very time-consuming. For this reason, square frozen fillet blocks are presently produced only on a small scale aboard ships despite the fact the fish can be converted into fillets aboard ship immediately after their catch.
In Japan, the fishery products are processed aboard ship mostly by method (B). That is, fish just caught are converted merely to rounds, severed fish with dress severed fish with bones or fillets, which are immediately frozen aboard for transportation. After these half-processed fishery products are brought to a processing place on land, they are unfrozen and converted to boneless and skinless fillets by removing bones and skins as desired. From these fillets square frozen blocks are produced in the manner as described. This means that in the case of method (C) the frozen products once prepared have to be unfrozen and frozen once again. This will lead to great deterioration of the quality. Besides, unnecessary portions of fish, such as bones and skins, must be transported together with the meat aboard the ship. This leads to an increase of the transportation cost, which will be considerable when fishing is carried out on seas far away, e.g., seas off the coast of Africa which is quite remote from shore processing facilities.